STOCK Droid 2 Extended batt upgrade DOES fit the Droid 1 and IS functional. The door included with the battery fits without ANY modification, direct fit.
Theres probably a few threads floating around already but go buy one while they still have them in stock before this secret is out hah.
The biggest difference I notice is while in my work area my service is terrible... about a 20% difference or so in usage during the daytime.
Only adds about 2mm at most of thickness on the back side, cant even really tell. The color is still black but with a shade of blue sparkle it appears. You can only really tell in direct light. Even at that, still amazing.
Ide say a worthy purchase for anyone looking for a tad longer run between charges